The present invention relates to a retaining spring for automobile sunvisor hinges which can hold any position among possible positions selected by a user.
It is well known that the sunvisor hinges normally fitted as a original equipment in automobiles comprise, in essence, a body member defined by the frame of the sunvisor or attached to said frame, and also attached to a retaining spring in such a way that said body member and retaining spring cooperate to receive a pivot pin of the bent support attached to the automobile structure.
The above described unit allows the sunvisor to occupy any position among those which are regularly used. The position occupied by the sunvisor is held by the gripping action of the retaining spring on the pivot pin of the bent support. Thereby are the vibration caused by the vehicle when being driven are from causing untimely movement of the sunvisor.
Generally the retaining spring and the pivot pin of the bent support are provided with corresponding mechanical means, which usually consist of positioning flats formed on said spring and pivot pin, and allow the rest positions of the sunvisor to be held more firmly.
In this way, the sunvisor hinge retaining spring applies pressure in two well differentiated ways to the pivot pin of the bent support. On the one hand, there is a first type of pressure for the sunvisor positions other than the rest positions and, on the other hand, a second type of pressure for the sunvisor rest positions. Thus, the passage of the sunvisor from the rest positions to any other position and vice versa, which passage hereinafter with regard to the retaining spring will be called working cycle, subjects the retaining spring to repeated resilient deformation which causes fatigue of the component material thereof, generally steel. This fatigue of the material causes a loss of resilience in the retaining spring and consequently a slackening of the grip on the pivot pin of the bent support. Thereby, under these conditions, the position occupied by the sunvisor becomes unstable and the vibrations of the vehicle when being driven cause untimely movement of the sunvisor which, apart from being troublesome, may cause situations of danger.
As examples of known of retaining springs for automobile sunvisors, there may be cited Spanish utility model number 292644, equivalent to U.S. Pat. No. 4,778,160, and Spanish patent number P 8900980, both having as title "Spring for automobile sunvisor hinges". In Spanish utility model number 292644, the retaining spring consists of a steel leaf, which is formed as a quadrangular prism having rounded edges, with one of the sides acting as a flexible wing pressing on the pivot pin of the bent support. In Spanish patent number P 8800980, the retaining spring consists of a steel sheet which is formed with four essentially rectangular tabs, with one tab extended with a curved extension defining a housing for the said pivot pin and gripped by said tabs and curved extension.
In the known sunvisor hinge springs the operative reliability is limited by a low number of working cycles after which they break or lose resilience and consequently slacken their grip on the pivot pin of the bent support, causing untimely release of the sunvisor.